The purpose of this study is to determine whether men over the age of 65 years with increased bone turnover will have decreased bone mass and thus an increase in fractures. It is hypothesized that aromatase inhibition, which blocks the conversion of testosterone to estradiol, will lead to an increase in bone turnover in men. If this hypothesis is correct, then better understanding of the pathogenesis of osteoporosis will lead to improved evaluation and therapy of osteoporosis in older men. The relationship between baseline bone turnover, calcium regulating and sex hormones and bone mass will be examined and compared with findings after 9 weeks of aromatase inhibition therapy.